Pusher pawl mechanism for power and free conveyor system

ABSTRACT

A power and free conveyor system has trolleys which are mounted on a free track for driving when engaged by pushers on a continuously running power chain. On each trolley, a pusher pawl, lost motion link, and bellcrank lever are interconnected to hold the pusher pawl erect for engagement by a pusher when the lever is in a normal position. When the lever is pivoted by engagement with a preceding trolley, the pusher pawl can collapse. The lost motion link also permits collapse of the pusher pawl on overtaking a pusher.

L. g gs i United States Patent 191 Peter [54] PUSHER PAWL MECHANISM FOR POWER AND FREE CONVEYOR SYSTEM June 4, 1974 Primary Examiner-M. Henson Wood, .lr.

Assistant Examiner-Robert Saifer Attorney, Agent, or Firm-J. F. Verhoeven; C. E. Tripp [5 7] ABSTRACT A power and free conveyor system has trolleys which are mounted on a free track for driving when engaged by pushers on a continuously running power chain. On

each trolley, a pusher pawl, lost motion link, and bellcrank lever are interconnected to hold the pusher pawl erect for engagement by a pusher when the lever is in a normal position. When the lever is pivoted by engagement with a preceding trol1ey, the pusher pawl can collapse. The lost motion link also permits collapse of the pusher pawl on overtaking a pusher.

4 Claims, 7 Drawing Figures [52] US. Cl. 104/172 S [51] Int. Cl. B65g 17/42 [58] Field of Search 104/172 S, 178, 172 C [56] References Cited UNITED STATES PATENTS 3,200,768 8/1965 Harrison 104/172 S 3,420,188 l/l969 Dehne et al. l04/l72 S 3,559,586 2/l97l Follrath 104/172 8 3,602,148 8/l97l Swartz l04/l72 S BACKGROUND OF THE INVENTION In a typical power and free conveyor system, a power track on which a power chain travels is closely spaced to a free track on which load trolleys travel. The power chain is driven, usually continuously, during operation by a motor and has spaced pushers thereon. These pushers drive the load trolleys on the free track, usually through a pusher pawl mounted on each load trolley.

One known method of disengaging the load carrying trolley from the driving chain pusher is to diverge the power and free tracks at a point or points where it is desired to stop the load trolley, as for loading or unloading. Another known method of disengaging the load carrying trolley from the driving chain pusher is to collapse the pusher pawl. It is this latter method of drive disengagement to which the present invention is directed.

In a system of the type in which the pusher pawl collapses to release the load trolley from the continuously driven driving mechanism, it is known to have a lever mounted on the trolley which is tripped either by a stop placed in the path of the trolley or by a preceding trolley.

SUMMARY OF THE INVENTION In the present invention, simple effective structure is provided on the load trolley in a power and free conveyor system for the transmission of driving motion to the trolley. In the preferred form of the invention, a pivotal bellcrank lever has a forwardly projecting leg and a normallyvertical leg which has a pivotal link mounted at the upper end thereof. A pivotal pusher pawl is mounted on the trolley adjacent the link and is connected thereto by means of a lost motion connection. The lost motion connection consists of a slot in the link and a pusher pawl projection which is received 7 in the slot.

. The lever, link, and pusher pawl are all pivotal about axes transverse to the direction of motion of the pusher. The pivot axis for the pusher pawl, which is of triangular shape, is behind the pivot axes of the link and lever (relative to. the forward direction of travel of the pusher). When the lever leg is upright, the bottom of the slot in the link defines an abutment surface which is engaged by the projection on the pusher pawl to hold a drive surface on the pusher pawl upright for engagementby th pusher. When the leveris tilted by engagement, for example, with the preceding trolley, the link is cocked and retracted, to retract the abutment surface, and allow the pusher pawl to pivot out of the path of the pusher.

The lost motion between the link and the pusher pawl permits the pusher pawl to pivot away from the abutment surface in the link at any time, so that the pusher pawl on the trolley can overtake a pusher atany time.

It is therefore one object of the present invention to provide an improved pusher pawl on a load trolley in apower and free conveyor system characterized by simplicity of construction and effectiveness of operation.

It is another object of the present invention to provide an improved load trolley pusher pawl which is held against collapse when urged in one direction and which freely collapses when urged in the opposite direction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in side elevation, with parts broken away for clarity, showing a power and free conveyor system embodying the present invention.

FIG. 2 is a view taken on the line 2-2 of FIG. 1.

FIG. 3 is a diagrammatic illustration of the pusher pawl held in a driving position by the link.

FIG. 4 is a view like the view of FIG. 3 except with the link retracting from the pusher pawl holding position.

FIG. 5 is a view like the view of FIG. 4 except with the link fully retracted from the pusher pawl.

FIG. 6 is a view like the view of FIG. 5 except showing the pusher pawl collapsed by a pusher.

FIG. 7 is a view like the view of FIG. 3 except showing the pawl collapsed reversely (from the direction of collapse of FIG. 6) as the trolley overtakes a pusher.

DESCRIPTION OF THE PREFERRED EMBODIMENT from pushers 10 through a pusher pawl 14 on the trolley when the pusher pawl is erect. The pusher pawl can be collapsed to stop the trolley, and the pusher pawl will freely collapse when the trolley overtakes a pusher.

In the power section of the conveyor, an I beam 20 has two opposed lower flanges 22 (only one of which is shown) which define a track for a plurality of power trolleys 24. Each power trolley has a pair of rollers 26 (only one roller of each pair shown) straddling the I beam for engagement with the upper. surfaces of the I opposed flanges 22. The power trolleys support an endless chain 28 which is continuously driven (during operation of the conveyor) by a motor (not shown). Each power trolley carries one of the pushers l0 hanging downwardly therefrom.

In the free section of the conveyor, a pair of opposed channels 30, 32 each has a lower flange 34, 36, the upper surfaces of which define opposed tracks for the free trolleys 12. Each trolley 12 has a pair of spaced apart sideplates 40 with a transverse hub 42 extending therethrough. An axle 44 through the hub carries rollers 46 at each. end which are received on the flanges 34, 36. Guide rollers 48, mounted on a vertical stub axle secured between the sideplates, fits between the inner edges of the lower flanges 34, 36 to prevent any significant side-to-s ide sway of the free trolleys. A bracket 50 for supporting a load (not shown) is suspended from a pin 52 extending through the sideplates 40. A bracket 54 supports a ramp 56 at the rear end of each trolley. Thus, in the absence of a restraining force, the trolleys 12, which are not connected to each other, are free to roll along the flanges 34, 36.

The power section of the conveyor, and the free trolleys 12 as thus far described, are conventional and have been used heretofore.

A propelling force is transmitted from individual pushers to each trolley 12 through an improved novel mechanism about to be described. A bellcrank lever 60 is pivotally mounted between sideplates 40 on a transverse pin 62 for rocking movement about transverse axis A. The lever has a lower leg 64 extending in a generally forwardly direction and an upper leg 66 extending in a generally upwardly direction. The lower leg 64 terminates in a pad 68, which, when it engages the ramp 56 of the preceding conveyor, tilts the lever clockwise (as viewed in FIG. 1) about axis A. The extreme limits of movement of lever 60 is defined by hub 42 (extreme counterclockwise movement) and a pin 70 (extreme clockwise movement) extending between the sideplates 40.

-The pusher pawl 14 is triangular shaped and is received between sideplates 40 and pivots about a transverse axis B defined by a transverse pivot pin 74. The pin 74 extends through the sideplates 40 and through one corner of the pawl 14. The pawl 14 has a leg 76 which extends in a generally forwardly direction (when the pin is oriented as shown on the right hand trolley in FIG. 1) and a leg 78 which extends in a generally upwardly direction when the pawl is so oriented. The forward leg has a pin 80 extending therethrough to define projections on each side of the pawl. The upwardly extending leg 78 has a flat rear contact surface 82 for engagement by the pusher 10 when the pawl is in the position shown on the right hand trolley in FIG. 1.

The position of the pusher pawl 14 is controlled by movement of the lever 60 which is operated by the ramp-56 of the preceding trolley (or by a similarly shaped stop member (not shown) positioned in the path of the trolley to stop the trolley). It is desired to remove the pusher pawl 14 of a trolley from the path of the pushers 10 when the trolley reaches a preceding trolley, or when a stop member having a ramp similarto ramp 56 is placed in the path of the trolley. It is also necessary to securely hold the pawl in the path of a forward moving pusher 10 when no trolley or stop member is in the path of the trolley. At the same time, how- I ever, it is desirable that a trolley which overruns a pusher be able to move freely past the pusher so that he Pus er wi l 93119 9. t trolley behind h pu h These rather complex requirements are met by the insertion of a pair of intermediate links 84 between the lever 60 and the pawl 14. The upper leg 66 of lever 60 terminates in a hub 86 (FIG. 3) which receives a pivot pin 88 on a transverse axis C. The links 84 are pivotally mounted at one end on pin 88, in straddling relation to leg 66. Extending inwardly from the opposite end are slots 90 in'the links which terminate in abutment surfaces 92. The projections 80 on pusher pawl 14 are received in the slots 90 and define with the slots a lost motion connection between the links 84 and the pusher pawl 14. Although the slots are open ended, the projections 80 of the pusher pawl remain in the slots since the limits of extreme movement of the pusher pawl (abutment surface 92 for extreme counterclockwise movement arid a pin 94 between sideplates 40 for extreme clockwise movement) will no permit disengagement of the pusher pawl from the links.

The operation of the mechanism through which power is transmitted from the continuously forwardly moving pushers 10 and the trolleys 12 can best be understood by reference to FIGS. 3 to 7. When the lever 60 is in the normal driving position (as the lever 60 of the right hand trolley FIG. 1), the upper leg thereof is substantially vertical. At that time, the projections and slots are directly above the upper leg of the lever. In other words, the projections 80 are in a substantially straight line with axes A and C, and the pusher pawl 14 is securely held against counterclockwise rotation (as viewed in FIG. 3) about axis B. Thus a pusher engaging the rear surface 82 of the pusher pawl will move the trolley forward (to the left as viewed in FIG. 3).

It should be noted, however, as shown in FIG. 7, that the pusher pawl 14 can freely rotate clockwise about axis B by virtue of the lost motion connection between pusher pawl 14 and links 84 which permits the projections 80 to rise in slots 90. Thus, a pusher pawl 14 can overtake a pusher 10.

As a trolley approaches a preceding trolley (or a stop member with a ramp similar to the ramp 56), the pad 68 will ride up the ramp, thereby tilting the lower leg 64 of lever 60 up and tilting the upper leg 66 rearwardly. When this occurs, the abutment surface 92 of the links is drawn away from the position where it supports the pusher pawl in an erect position to permit the pusher pawl to swing counterclockwise, as shown in FIGS. 4 and 5. Thus, a pusher 10 will collapse the pawl, as shown in FIG. 6, and leave the trolley 12.

The weight of the pad 68 is sufficient to allow the lever 60 to swing counterclockwise (from the position of the lever on the left trolley of FIG. 1 to the position of the right trolley on FIG. 1) when the preceding trolley is advanced (or a stop member removed from the path of the trolley). At that time, the links 84, being restrained by the projections 80, will swing back to the position of FIG. 3 to again hold the pusher pawl erect for engagement by the next pusher.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made withoutdeparting from what is regarded to be the subject matter of the invention.

1 What is claimed is:

1. In a power and free trolley system having a trolley movable along a track and having a pusher movable in a forward direction to drive the trolley. the combination comprising means defining a stop member positionable in the path of the trolley, a lever pivotally mounted on the trolley and normally held in a drive position, said lever movable from said drive position in response to engagement'with said stop member, a pusher pawl mounted on the trolley for pivotal movement about an axis, said pusher pawl having a projection thereon, and a link pivotally connected to said lever and movable thereby when the lever is moved, said link having a slot therein.

to receive the projection on the pusher pawl and hold the pusher pawl erect for engagement by a pusher .When dcveris iathe. d npa fio 2. The mechanism of claim I in which the bottom of said slot defines an abutment surface to hold the pusher pawl against collapse when engaged by a pusher pawl movingjn the forward direction, said pusher pawl pivoting about said a risandthe projectionthereon moving in the slot away from said abutment surface to permit? collapse of the pusher pawl when engaged by the? pusher moving opposite to the forward direction i 3 In a power and free trolley system having a trolley movable along a path and having a pusher to? move the trolley, the combination comprising means defining a stop member in the path of the trolley, ai lever on the trolley movable from a drive position in response to approach of the trolley to said stop member, a pusher pawl pivotally mounted on the trolley,.. a link pivotally connected to said lever, and means defining a lost motion connectionbetvveen the and the pawl to hold the pawl against collapse in one direction when the lever is in a drive position and to permit collapse in the opposite direction, said means defining a lost motion connection between said pusher pawl and said link including a slot in said link, the bottom of said slot defining an abutment surface for engagement by the pusher pawl when the lever is in a drive position to hold the pusher pawl in the path of the pusher. V

4. The mechanism of claim 3 in which the abutment surface defined by the bottom of the link slot is shifted in response to movement of the lever from the drive posntq rm aps o the srspawl 

1. In a power and free trolley system having a trolley movable along a track and having a pusher movable in a forward direction to drive the trolley, the combination comprising means defining a stop member positionable in the path of the troley, a lever pivotally mounted on the trolley and normally held in a drive position, said lever movable from said drive position in response to engagement with said stop member, a pusher pawl mounted on the trolley for pivotal movement about an axis, said pusher pawl having a projection thereon, and a link pivotally connected to said lever and movable thereby when the lever is moved, said link having a slot therein to receive the projection on the pusher pawl and hold the pusher pawl erect for engagement by a pusher when said lever is in the drive position.
 2. The mechanism of claim 1 in which the bottom of said slot defines an abutment surface to hold the pusher pawl against collapse when engaged by a pusher pawl moving in the forward direction, said pusher pawl pivoting about said axis and the projection thereon moving in the slot away from said abutment surface to permit collapse of the pusher pawl when engaged by the pusher moving opposite to the forward direction.
 3. In a power and free trolley system having a trolley movable along a path and having a pusher to move the trolley, the combination comprising means defining a stop member in the path of the trolley, a lever on the trolley movable from a drive position in response to approach of the trolley to said stop member, a pusher pawl pivotally mounted on the trolley, a link pivotally connected to said lever, and means defining a lost motion connection between the link and the pawl to hold the pawl against collapse in one direction when the lever is in a drive position and to permit collapse in the opposite direction, said means defining a lost motion connection between said pusher pawl and said link including a slot in said link the bottom of said slot defining an abutment surface for engagement by the pusher pawl when the lever is in a drive position to hold the pusher pawl in the path of the pusher.
 4. The mechanism of claim 3 in which the abutment surface defined by the bottom of the link slot is shifted in response to movement of the lever from the drive position to permit collapse of the pusher pawl. 